This invention relates to dispersants or dispersing agents and particulate dispersions including nanoparticle dispersions.
Nanoparticles of metal oxides and metal borides, specifically, those of zinc, zirconium, cerium, titanium, aluminum, lanthanum, indium and tin have important commercial applications. Nano zirconia, ceria and alumina are of interest for scratch resistant coatings and heat transfer fluids. Additionally, aluminum metal nanoparticles that have been passivated with a thin layer of aluminum oxide are of use in the development of energetic materials. Indium tin oxide (ITO) nanoparticles have applications in clear conductive coatings, in heat management layers, and in static charge dissipation. Zinc oxide and titania (TiO2) are of interest for UV blocking applications, including sunscreens, clothing and coatings. Other applications of metal oxide nanoparticles and/or nanoparticles that have a metal oxide surface include magnetic materials, heterogeneous catalysts, toner compositions, and ceramics.
In order to supply nanoparticles and/or microparticles for expedient use as dispersions for master batches or in fully formulated compositions, the particles must be dispersed in various liquids and polymeric matrices. The quality of the dispersion should be commensurate with its intended use. For example, the presence of color or haze is unacceptable in many applications, including inks and coatings. In addition, the dispersion is preferably stable so it does not have to be prepared immediately before use, but can be stored after preparation.
US Patent Application Publication No. 2003/0032679 describes the dispersion of nanoparticles in solvents using commercially available dispersants; the disclosure of which is hereby incorporated by reference.